Machining of Metal Matrix Composite - process modelling, tool wear and surface integrity

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During the past decades, Metal Matrix Composites (MMCs) have received considerable interests in several manufacturing sectors including the automotive and aerospace industries which represent a major sector of the Canadian manufacturing economy. MMCs possess superior physical and mechanical properties compared to non-reinforced alloys. Therefore, they are being considered as a replacement material for the conventional alloys in many engineering applications. Their unique physical properties give them a great potential; however, MMCs face challenges in order to have a wide spread MMCs substitution for monolithic materials. The presence of abrasive reinforcements in the ductile matrix causes severe tool wear and premature tool failure during machining operation. Although efforts have been made to produce MMCs parts by casting, or hot forging, the resulted near net-shape products still have to be machined into the final shape and dimension with the required accuracy. Cracking and debonding of the reinforcement particles are the significant damage modes of machined surface and also the subsurface damage assessment is critical for machined components subjected to fatigue, especially in critical application such as aerospace. The changes in the machined surface physical properties and machining induced residual stresses are attributed to both mechanical as well as thermal load (heat generated). One way to overcome this challenge is by reducing/eliminating the harmful effect of tool wear. The previous successful application of self-propelled rotary tool in cutting other difficult to cut materials has made it a good candidate for better control of tool wear and tool life when cutting MMC.           In view of the growing application of these materials, the detailed study of their machined surface integrity and improvement of their cutting process efficiency is required. This study will focus on the above mentioned challenges through detailed surface integrity study of machined MMC surfaces and provide the needed knowledge and expertise to enable the wide use of this material in several Canadian industries.